Add missing production DFP docstring (#1076)

- Add docstring to DFPPreprocessingStage

Close #609

Authors:
  - Eli Fajardo (https://github.com/efajardo-nv)

Approvers:
  - Michael Demoret (https://github.com/mdemoret-nv)

URL: #1076

examples/digital_fingerprinting/production/morpheus/dfp/stages/dfp_preprocessing_stage.py

@@ -27,13 +27,23 @@
 
 from ..messages.multi_dfp_message import MultiDFPMessage
 
-logger = logging.getLogger("morpheus.{}".format(__name__))
+logger = logging.getLogger("morpheus.{__name__}")
 
 
 class DFPPreprocessingStage(SinglePortStage):
-
-    def __init__(self, c: Config, input_schema: DataFrameInputSchema):
-        super().__init__(c)
+    """
+    This stage performs preprocessing on incoming DataFrame as defined by `input_schema` before training or inference.
+
+    Parameters
+    ----------
+    config : `morpheus.config.Config`
+        Pipeline configuration instance.
+    input_schema : `morpheus.utils.column_info.DataFrameInputSchema`
+        Input schema for the DataFrame.
+    """
+
+    def __init__(self, config: Config, input_schema: DataFrameInputSchema):
+        super().__init__(config)
 
         self._input_schema = input_schema